Replace the original FM.EXE in the installation folder with this bad boy:
http://dl.gamecopyworld.com/?d=2006&f=rld-fm6f!rar
(it's probably a good idea to keep a copy of the original fm.exe file as well. Just rename it fm1.exe and you can change in back later if needs be).
If it works it's all gravy, if not you'll need to do the following:
Go to start>run> and type in 'regedit' and press enter.
First back up the registry. Do this by going to the file menu and clicking on export. Choose a save location (this is incase the registry gets fucked up so you can restore it to its previous state. This will mean there's no risk to doing the next stage).
Browse to HKEY_CURRENT_USER>software>sports interactive>football manager 2006
Right click on version 63 or 6.0.3 and rename to version 6.0.2.
Exit and it's done
